Controlling Nanoantenna Polarizability through Backaction via a Single Cavity Mode

Area of Science:

• Optics and Photonics
• Materials Science
• Nanotechnology

Background:

• Polarizability (α) governs light interaction with small particles, influencing absorption, extinction, and scattering.
• Particle polarizability is not solely dependent on size and material but can be modified by the photonic environment (backaction).

Purpose of the Study:

• To investigate and control the backaction between broadband scatterers and a single-mode optical cavity.
• To demonstrate how backaction can be used to tailor the radiative properties of nanoparticles.

Main Methods:

• Utilized a microtoroid ring resonator as a high-quality cavity.
• Employed an array of nanorods as broadband scatterers.
• Exploited diffractive properties of the nanorod array to control backaction strength.

Main Results:

• Demonstrated that backaction from the microtoroid resonator significantly alters nanorod polarizability.
• Observed polarizability renormalization due to field scattering and depolarization effects within the cavity.
• Showed that backaction strength can be tuned by manipulating the array's diffractive properties.

Conclusions:

• Backaction is a viable mechanism for tailoring nanoparticle optical properties.
• Hybrid plasmonic-photonic resonators can be engineered by controlling scatterer-cavity interactions.
• Understanding coupled optical resonators is advanced by studying these perturbation effects.